1. Field of the Invention
The present invention relates to erosion control blankets for inhibiting ground erosion in flat or sloping, often bare earth areas, or channels, where water flows, and, more particularly, but not by way of limitation, to fibrous erosion control blankets adapted to permit ground vegetation to grow upwardly therethrough and manufactured without conventional netting.
2. History of the Prior Art
For both aesthetic and environmental protection reasons, it is often necessary or desirable to grow ground vegetation, such as grass, on flat land or slopes, channels, and bare earth areas to inhibit erosion due to the effects of wind and rain. The successful sprouting and growth of ground vegetation planted on these areas, however, is often prevented by the soil erosion which the planted vegetation is designed to inhibit, the erosion frequently carrying away at least some portion of the soil before it the vegetation takes hold.
To alleviate this problem, it is now a common practice to cover the area with fibrous, mat-like members commonly referred to as erosion control blankets. One particularly effective erosion control blanket is the CURLEX® or excelsior blanket manufactured and sold by the American Excelsior Company of Arlington, Texas since 1964. This erosion control blanket is fabricated, in elongated rectangular mat form, from elongated, randomly intertwined fiber commonly referred to as “excelsior” or “wood wool.” The fiber mats have historically been held together or contained by photodegradable or netting material, which form nets on one or both sides of the fiber. The blanket-net assemblies are then conveniently packaged in individually rolled bundles to facilitate their handling and transport to the erosion control job site. The netting is generally necessary during manufacturing, shipping and the subsequent job site installation in order to maintain the integrity of a fibrous mat.
At the job site, the blanket bundles are unrolled in a side-to-side relationship along the earth area to be protected against erosion, and are secured along the sides of one another and to the underlying ground area with the use of a spaced series of conventional ground staple members, which may be made of steel, wood, plastic or starch. The installed blankets generally have parallel sides and abut one another to form a substantially solid surface to shield the underlying earth area, and thus the planted ground vegetation therein, from wind and water erosion forces.
The individual fibers forming the mat portions of various types of the blankets collectively define therebetween a multiplicity of small interstitial regions through which the planted ground vegetation may upwardly sprout and grow. During such shielded vegetation growth, some varieties of the blankets, such as the CURLEX® blanket decompose, ultimately being replaced by the emerging ground vegetation.
Despite the erosion control effectiveness of these excelsior/wood wool blanket-net assemblies, and similar blankets formed from other fibrous-net materials, erosion control blankets of this general type have a distinct disadvantage. The problem pertains to the use of the netting material often utilized to contain the fiber. Although the netting may be photodegradable, it may last long enough to present ecological and maintenance problems. It has been reported that conventional netting is capable of trapping birds and other small wildlife attempting to nest or inhabit the erosion control blankets. Until the netting material photodegrades, it does present an ecological impediment to normal animal activity. In addition, the netting, which often forms a large grid of material that can become entangled in mowing equipment before the material photodegrades.
In U.S. Pat. No. 5,735,982, herein incorporated by reference in its entirety, a net free erosion control blanket is described. As described therein, the erosion control blanket is held together by a bonding agent such as latex. Although, the above-described blanket does not include a net and therefore provides the advantages of a net-free assembly, the use of latex is, in some instances, cost prohibitive. In those instances where the entire erosion control blanket must biologically degrade as does excelsior/wood wool, a different system of securement for the excelsior/wood wool fibers is necessary. The present invention provides such a system by incorporating a stitching technique, which in conjunction with the intertwined relationship of the excelsior/wood wool fibers, as described herein, provides an effective erosion control blanket that is environmentally friendly.